An AI language tutor that works without internet
Most apps that call themselves “offline” mean offline flashcards and vocabulary lists — the moment you want to actually practise a conversation, you need a connection again, because the AI doing the talking lives on a server somewhere. Sayelle is different: the tutor model, speech recognition, and text-to-speech all run on your iPhone. Once you've downloaded them, a real back-and-forth conversation works the same on a flight, in a subway tunnel, or anywhere else with zero signal.
What actually runs on your device
Three models download once, over Wi-Fi (about 4 GB total), and then live on your phone: the tutor language model that generates replies, a speech recognition model that transcribes what you say, and a text-to-speech model that reads its answers back out loud. None of the three need a server round-trip to work. That means the actual conversation — the part where you speak, the tutor listens, and it answers — has no per-message latency waiting on an API, and no data about what you said leaves your phone for that exchange.
What still needs a connection
To be precise rather than oversell this: signing in, purchases, ads, Cloud Sync, and downloading new lesson/scenario content all need internet access. If you're signed in with Cloud Sync on, your text transcripts and progress sync to Sayelle's backend when you're connected again — but the conversation itself, the speaking and listening and replying, doesn't wait on that. See the FAQ and Privacy Policy for the complete picture.
Why running the AI locally actually matters
Beyond just working on a plane, on-device processing means your voice isn't being streamed to a server to generate a reply — raw microphone audio is processed transiently on your phone and is never uploaded. It also means the app doesn't depend on a third-party AI provider's uptime or rate limits for its core feature to function; the model that talks to you is the one actually sitting on your phone.
How this compares to other “offline” language apps
Several well-known language apps advertise offline modes, and they're genuinely useful — for reviewing vocabulary, replaying downloaded audio lessons, or working through spaced-repetition flashcards without a connection. Where most of them still need internet is the part that actually resembles a conversation: an AI that listens to open-ended speech and responds naturally, rather than picking from a fixed lesson script. That specific capability — a real, unscripted conversation, not a downloaded audio file — is what runs fully on-device in Sayelle.
Try it
Sayelle is free to start, with nine languages supported today — English, Spanish, French, Italian, Portuguese, German, Chinese, Hindi, and Japanese. Download it on the App Store or read more on the homepage.